Parrotts Ferry Bridge

From HighestBridges.com

Parrotts Ferry is a submerged reservoir bridge whose piers are usually hidden beneath New Melones Lake in Central California’s Calaveras County. At 640 feet (195 mtrs), the main span is one of the longest prestressed concrete beam bridges ever built in the United States. One of the earliest bridges to use a special lightweight concrete, the central span had sagged nearly a foot about 5 months after opening and nearly another foot in the ten years that followed. Concerned about the displacement, tests were done to the bridge and it was decided to add a large bracing span underneath the central third of the bridge to prevent any further sagging. The bridge has been performing perfectly ever since.

Downstream of Parrotts Ferry is the Archie Stevenot bridge, one of the highest reservoir bridges in the United States. The multi-span steel box girder bridge carries route 49 across the Stanislaus River and the New Melones reservoir. Rising approximately 400 feet (122 mtrs) from foundation to cap, the central pier is tied with California’s Auburn Foresthill as the tallest ever built in the United States. Both bridges were completely out of the water in 1992 from a severe drought. I know of no reservoir in North American history that ever dropped more than 367 feet (112 mtrs) as the New Melones Lake did during October of that year. You can check on current levels at http://cdec.water.ca.gov/reservoir.html.